Perspective drawing kit



March 1959 c. R. SPENCER ETYAL ,876,547

PERSPECTIVE DRAWING KIT Filed July 15, 1953 rates PERSPECTIVE DRAWING KIT Application July 13, 1953, Serial No. 367,494

' 3 Claims. or. 33-77 This invention relates to mechanical drawingdevices and more particularly toa device which facilitates the execution of angular perspective drawings.

Perspective views are used for various purposes, such views provide non-technical personnel with at; least a fair understanding. of a. complex device or apparatus. Frequently engineers and draftsmen use a perspective view as an aid in visualizing a complex device which is shown in accompanying orthographic drawings. Perspectives are also extensively used for illustrative purposes in maintenance and repair manuals, in fact any place where a pictorial view of a device is required.

Although perspective views are extremely useful and are used to a certain extent, their. execution by conventionalmeans requires an extensive drawing surface andv may prove bothersome to many draftsmen, accordingly they are not used as extensively as they should be. Briefly the instant invention discloses a drawing device which comprises an especially constructed drawing board and- T-square, the drawing board having apair of arcuate slots formed to accommodate the head of the Tasquare: and automatically position the blade thereof so that. horizontal lines of a device or structure may be located and drawn in perspective on the drawing surface of the.

board. The drawing board and T-square are also provided with scales whereby correct perspective measure-- ments may be applied directly to the drawing.

Accordingly it is an object of the present invention to provide adrawing device whereby. the execution of" perspective drawings is materially facilitated.

Another object is to provide a drawing device utilized; in executing perspective-drawing which eliminates the: necessity of extensive construction lines.

Another object is to provide a drawing. device utilized.- in executing perspectivedrawings which requires mate-- rially less drawing surface than if conventionalmethodswere used.

Another object is to provide a drawing device utilized. in executing perspective drawings which provides grad-- uated scales whereby measurements may be applied directly to the drawing.

These and other objects will become moreapparent: from the following descriptionand drawing in which like reference characters denote like parts: It isto be expressly understood, however, that the drawing is forthepurpose: of illustration only and not" a definition of the limitsofi the invention, reference being had ifor-this' purpose-'to-the: appended claims.

In the drawing:

Figure 1 is a perspective view of 'a preferred embodiment of a drawing board and T-square-constructed as disclosed herein.

Figure 2 is an enlarged perspective view ofthe T-square as shown in Figure 1.

Referring to the v accompanying drawing, Figure I. shows a rectangular drawing board 11 either side of which. may be used as a drawing surface 12 for the. execution of? perspective drawings. Formed in the board'a're a pair of ment arcuate slots 13 and 14, these slots are identically located in the upper corners of the board and are equally spaced on each side of the vertical center line 15 thereof. The edges 16 and 17 of slot 13 and edges 18 and 19 of slot 14 constitute cylindrical surfaces having common axes 20 and 21, respectively. The axes (20 and 21) are located on a common horizontal line 22 and spaced at. equal distances on each side of center line 15, the line 22. constituting the horizon of a perspective drawing 23 executed on the drawing surface 12. Surfaces 16 to 19, inclusive, are normal to the drawing surface of the board, this is also true of the surfaces defining the end portions of the arcuate slots. Axes 20 and 21, which in the present instance lie beyond the right and left side of the drawing board, respectively, also represent the right and left hand vanishing points of the drawing 23 and would be used in its execution if it was to be drawn by conventional methods. The slots 13 and 14 preferably extend through the entire thickness of the board thus eliminating the possibility of foreign material collecting therein which may aiiect the accuracy of the device. The extent of slots 13 and 14, that is the relative location of their end portions with respect to the drawing surface, will be described further as the disclosure progresses.

A pair of spaced vertical scales 24 are provided at equal distances on each side of the vertical line '15 and extend downwardly from line 22 toward the lower por- 7 tion of the drawing surface 12, substantially as shown in Figure 1. These scales are identical and the spaces between their graduations equal, the graduations are used to determine vertical distances which lie in the picture plane of drawing 23 and also to determine the configuration of circular areas in perspective located in a horizontal plane. Accordingly each of these scales have two. sets of markings, one for linear measurements indicated at 25, the other for determining the elliptical configuration of circular areas indicated by numeral 26. The mark.- ings 25 begin with zero, at the intersection of scales 24 with line 22, and increases in numerical value from this point to the lower ends of the scales, these markings may be in inches or any linear unit desired. Mark-' ings 26 begin with fifteen degrees (15) at the fifth graduation below the intersection of scales 24 with line 22, thereafter each graduation represents one degree, however the degree markings are indicated at five degree intervals only. The method of using scales 24 for the two purposes mentioned above will be further described in connection with the operation of the device.

An especially constructed T-square 27, shown in detail in Figure 2, is adapted for usewith the drawing board described above. The T-square comprises a head. portion 28, generally of triangular. configuration, and a blade portion 29. The relationship of the head 28 and blade 29 is such that a longitudinal edge 30 of the blade and the plane surface of an edge 31 of the head are normal to each other, the end portions of edge 31 constitute cylindrical surfaces 32 and 33 having the same curvature as edges 16 and 18 of arcuate slots 13 and 14, respectively. The axes of surfaces 32 and 33 are normal to the triangular surfaces of the T-square head and intersect a line coinciding with edge ,30 at a point beyond the head of the T-square. The other longitudinal edge 34 of the blade 29 is positioned slightly oblique with re spects to the plane portion of edge 31 and coincides with a radial line originating at the coincident axes of surfaces 32 and 33. The blade portion of the T-square is located midway between the triangular faces of the head portion, this construction allows the T-square head to be used in, either arcuate slot. Accordingly with the head 28 posi-. tioned in first one and then the other of the arcuate slots the blade portion 29 extends across the drawing surface from the right or left to locate horizontally extending lines of the drawing 23. A graduated scale 35 is provided on each side of the T-square blade adjacent edge 30, the spaces between the scale graduations diminishing from the outer end of the blade toward head 28 in accordance with the rule of perspectives. These scales 35 are only applicable when edge 30 is inclined at an angle of twenty-five degrees (25) below the horizon (line 22), that is when a base line distance of drawing 23 is being measured.

With the T-square head in position in either arcuate slot, for example right hand slot 13 as shown by solid construction in Figure 1, surfaces 32 and 33 contact edge 16 of the slot which provides a guiding surface for the T-square head. Edge portions 36 and 37 of the head 28 are inclined at different angles with respect to the plane portion of edge 31, these portions (36 and 37) contact the end portions of slots 13 and 14 to limit the travel of the T-square head and accordingly the travel of blade 29. The edge portions 36 and 37 also aid in eliminating the possibility of placing the head 28 in either of the arcuate slots in an upside-down position. The slots 13 and 14 are positioned with respect to the drawing surface and extend so that the T-square may be moved between a first position in which edge 30 coincides with the horizontal line 22 and a second position in which edge 30 is positioned at an angle of twenty-five (25 below line 22. The T-square may be moved between the aforementioned first and second positions regardless of which arcuate slot the head is positioned in.

Thus it is seen a drawing device is provided in which distant vanishing points are not required in executing a perspective drawing on the drawing surface of the device. Also measurements may be applied directly to the drawings in accordance with the rules of perspectives. The function of the various'parts of the device will become more apparent from the following description in which the procedure for executing a simple perspective drawing is outlined.

In executing a perspective drawing on the drawing surface 12, e. g. the drawing 23 as seen in Figure 1, the need for locating vanishing points for the drawing is not necessary as horizontal lines are automatically located by edge 30 of the T-square at such times as its head portion is properly positioned in the arcuate slots 13 and 14. The base lines 38 and 39 of the drawing are first located by moving the T-square head to its lowest position in slots 13 and 14, respectively. The length of these lines are measured directly with scales 35. Vertical lines 40, 41 and 42 are then drawn at the intersection of lines 38 and 39 and at the ends of these lines, respectively. The length of vertical line 40, in the drawing, may now be determined by the linear markings on scales 24 in cooperation with the T-square. To determine the length of line 40, head 28 is moved upwardly in the slot in which it is positioned until the edge 30 has passed over a number of spaces on scale 24 equal to the actual height of the line, the intersection of edge 30 with line 40 now gives us the length of this line in perspective. It is now apparent how the remainder of the base portion of the structure of drawing 23 is executed. The length of base lines 43 and 44 of the superstructure may also be determined or measured by scale 35, such measurements being made on base lines 38 and 39 and then projected to their proper location in a conventional manner. The length of vertical line 45 may also be measured in a manner similar to vertical line 40 however this line (45) must be measured in the plane in which lines 38 and 40 or 39 and 40 lie. The remainer of the superstructure may then be completed. All vertical lines may be drawn by using the T-square and a triangle in a conventional manner or by using the T-square alone in conjunction with the top or bottom edge of the drawing board providing they are parallel with the horizon (line 22). The elliptical configuration of circular areas appearing in a horizontal plane are determined by placing the edge 30 of the T- square so it coincides with the intersection of two diameters of the area located at an angle with respect to each other. The configuration of the area is then determined by the intersection of edge 30 of the T-square with scales 24 as indicated by the elliptical marking 26. Such an area is represented at 46, all circular areas located above the fifteen degree (15") elliptical marking are shown as fifteen degree,(15) ellipses, all those between fifteen degrees (15) and twenty degrees (20) as twenty degree (20) ellipses, etc. Circular areas such as 47, located in a vertical plane, are shown as a forty-five degree (45 ellipsis which is customary practice in perspective drawmgs.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a preferred form of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

What is claimed is:

1. A device for executing a perspective drawing comprising: a drawing board portions of which define a pair of arcuate slots which define guiding edges which constitute identical cylindrical surfaces and in which said slots terminate in end edges having difierent angular relations with respect to said guiding edges; said slots being located with respect to each other with their guiding edges in'spaced opposed relation and the axes of said guiding edges intersecting a common line at positions on opposite sides of said drawing board; and a T-square including a head, having top and bottom faces, and an elongated blade having a ruling edge; said head having a first edge including a plane surface which terminates at each end in cylindrical surfaces having coincident axes and radii equal to the radii of said guiding edges; said blade being attached to said head midway between said top and bottom faces with said ruling edge extending normal to the plane surface of said first edge and said ruling edge if extended intersects the coincident axes of the cylindrical surfaces of said first edge; said head being generally of triangular configuration in plan view defined by said first edge and second and third edges, the latter edges having different angular relations with respect to the plane surface of said first edge; said head being positionable in either of said slots with the cylindrical surfaces of said first edge in contact with said guiding edges and when moved to one end of a respective slot said second edge contacts the end edge thereof in flush relationship to pc- I sition said ruling edge in a position locating the horizon slot in flush relationship to position said ruling edge in a position to locate base lines of said drawing.

2. Apparatus as set forth in claim 1 further characterized by including a pair of spaced graduated scales on said drawing board each of which extend in a direction normal to said common line and in which said graduations cooperate with said ruling edge to determine vertical distances which lie in the picture plane of said drawing and the elliptical configuration of circular areas which constitute part of said drawing.

3. Apparatus asset forth in claim 2 further characterized by including a graduated scale on said ruling edge and in which the spaces between the graduations constituting the scale on said ruling edge diminish from the outer end of said ruling edge toward said head in ac cordance with the rule of perspectives.

' (References on following page) 5 References Cited in the file of this patent 1,969,758 UNITED STATES PATENTS 21,336 Hansell Aug. 31, 1858 312,175 Speir Feb. 10, 1885 5 482,127 Johnson Sept. 6, 1892 203 211 1,591,380 Harmer July 6, 1926 6 McCoy Aug. 14, 1934 Fry Nov. 6, 1945 Andersen et a1. Dec. 10, 1946 FOREIGN PATENTS Great Britain Dec. 11, 1923 

